Solveeit Logo

Question

Chemistry Question on d -and f -Block Elements

The electronic configurations of Eu (Atomic No. 63), Gd(Atomic No. 64) and Tb (Atomic No. 65) are:

A

[Xe]4f65d16s2,[Xe]4f75d16s2{[Xe]^4f^6 5d^1 6s^2, [Xe]^4f^75d^16s^2} and [Xe]4f96s2{[Xe]^4f^9 6s^2}

B

[Xe]4f65d16s2,[Xe]4f75d16s2{[Xe]^4f^65d^16s^2, [Xe]^4f^75d^16s^2} and [Xe]4f85d16s2{[Xe]^4f^85d^16s^2}

C

[Xe]4f76s2,[Xe]4f75d16s2{[Xe]^4f^7 6s^2, [Xe] 4f^75d^16s^2} and [Xe]4f96s2{[Xe]4f^96s^2}

D

[Xe]4f76s2,[Xe]4f86s2{[Xe]4f^76s^2, [Xe]4f^86s^2} and [Xe]4f85d16s2{[Xe]4f^85d^16s^2}

Answer

[Xe]4f76s2,[Xe]4f75d16s2{[Xe]^4f^7 6s^2, [Xe] 4f^75d^16s^2} and [Xe]4f96s2{[Xe]4f^96s^2}

Explanation

Solution

63Eu    [Xe]4f75d06s2{_{63}Eu \; \Rightarrow \; [Xe] 4f^7 5d^0 6s^2}
64Gd[Xe]  4f75d16s2{_{64}Gd \, \Rightarrow \, [Xe] \; 4f^7 5d^1 6s^2}
half filled f subshell is more stable
65Tb  [Xe]4f95d06s2{_{65} Tb \, \Rightarrow \; [Xe] \, 4 f^9 \, 5 d^0 \, 6 s^2}